Rievtech ELC Series - Page 135

EN
Programmable Relay ● User Manual for ELC, EXM and PR Series 135 2020 v6.0 ● © Rievtech Co.,
Ltd. ● www.rievtech.com
regulated basics. The updated value PV is calculated in the
formulas.
Updated value PV = (PV * gain) + offset
If the updated value PV = SP, then the special function
does not change the value of AQ.
Dir = upwards/+ (timing diagram numbers 1 and 3)
If the updated value PV > SP, then the special function
reduces the value of AQ.
If the updated value PV < SP, then the special function
increases the value of AQ.
Dir = downwards/- (timing diagram number 2)
If the updated value PV > SP, then the special function
increases the value of AQ.
If the updated value PV < SP, then the special function
reduces the value of AQ.
With a disturbance, AQ continues to increase/decrease
until the updated value PV again corresponds to SP. The
speed with which AQ changes depends on the parameters
KC and TI. If the input PV exceeds the parameter Max.,
then the updated value PV is set to the value of Max. If
the PV falls short of the parameter Min., then the updated
value PV is set to the value of Min.
If the input R is set to 1, then the AQ output is reset. As
long as R is set, the input A/M is disabled.
Sampling Time
The sampling time is fixed at 500 ms.
Parameter sets
In order to simplify the use of the PI controller, the
parameters for KC, TI and Dir are predefined for the
following applications:
Parameter set
Application example
Parameter
KC
Parameter
TI (s)
Parameter
Dir
Temperatur
e fast
Temperature,
cooling control of
small spaces; small
volumes
0,5
30
+
Temperatur
e slow
Heating, ventilation,
temperature,
cooling control of
large spaces; large
volumes
1,0
120
+
Pressure 1
Quick pressure
change, compressor
control
3,0
5
+
Pressure 2
Slow pressure
change, differential
pressure control
(flow controller)
1,2
12
+
Full level 1
Vat and/or reservoir
filling without drain
1,0
1
+
Full level 2
Vat and/or reservoir
filling with drain
0,7
20
+
Control and regulated
In engineering, quantities can be both controlled and
regulated.
When controlling, a quantity is manipulated without being
able to compensate for outside influences. When
regulating, a quantity is maintained at a specific value in
order to compensate for outside influences.
In the following example, controlling means that the
person can set the heat output at a fixed value. The heater
cannot compensate for the drop-in room temperature
when a window is opened.